From: Jia He <redacted>

This is to let bool variable could be correctly displayed in
big/little endian sysctl procfs. sizeof(bool) is arch dependent,
proc_dobool should work in all arches.

Suggested-by: Pan Xinhui <redacted>
Signed-off-by: Jia He <redacted>
[thuth: rebased the patch to the current kernel version]
Signed-off-by: Thomas Huth <redacted>
---
  include/linux/sysctl.h |  2 ++
  kernel/sysctl.c        | 42 ++++++++++++++++++++++++++++++++++++++++++
  2 files changed, 44 insertions(+)

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index d99ca99837de..1fa2b69c6fc3 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h

@@ -48,6 +48,8 @@ typedef int proc_handler(struct ctl_table *ctl, int write, void *buffer,
  		size_t *lenp, loff_t *ppos);
  
  int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *);
+int proc_dobool(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos);
  int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *);
  int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *);
  int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 272f4a272f8c..25e49b4d8049 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c

@@ -536,6 +536,21 @@ static void proc_put_char(void **buf, size_t *size, char c)
  	}
  }
  
+static int do_proc_dobool_conv(bool *negp, unsigned long *lvalp,
+				int *valp,
+				int write, void *data)
+{
+	if (write) {
+		*(bool *)valp = *lvalp;
+	} else {
+		int val = *(bool *)valp;
+
+		*lvalp = (unsigned long)val;
+		*negp = false;
+	}
+	return 0;
+}
+
  static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
  				 int *valp,
  				 int write, void *data)

@@ -798,6 +813,26 @@ static int do_proc_douintvec(struct ctl_table *table, int write,
  				   buffer, lenp, ppos, conv, data);
  }
  
+/**
+ * proc_dobool - read/write a bool
+ * @table: the sysctl table
+ * @write: %TRUE if this is a write to the sysctl file
+ * @buffer: the user buffer
+ * @lenp: the size of the user buffer
+ * @ppos: file position
+ *
+ * Reads/writes up to table->maxlen/sizeof(unsigned int) integer
+ * values from/to the user buffer, treated as an ASCII string.
+ *
+ * Returns 0 on success.
+ */
+int proc_dobool(struct ctl_table *table, int write, void *buffer,
+		size_t *lenp, loff_t *ppos)
+{
+	return do_proc_dointvec(table, write, buffer, lenp, ppos,
+				do_proc_dobool_conv, NULL);
+}
+
  /**
   * proc_dointvec - read a vector of integers
   * @table: the sysctl table

@@ -1630,6 +1665,12 @@ int proc_dostring(struct ctl_table *table, int write,
  	return -ENOSYS;
  }
  
+int proc_dobool(struct ctl_table *table, int write,
+		void *buffer, size_t *lenp, loff_t *ppos)
+{
+	return -ENOSYS;
+}
+
  int proc_dointvec(struct ctl_table *table, int write,
  		  void *buffer, size_t *lenp, loff_t *ppos)
  {

@@ -3425,6 +3466,7 @@ int __init sysctl_init(void)
   * No sense putting this after each symbol definition, twice,
   * exception granted :-)
   */
+EXPORT_SYMBOL(proc_dobool);
  EXPORT_SYMBOL(proc_dointvec);
  EXPORT_SYMBOL(proc_douintvec);
  EXPORT_SYMBOL(proc_dointvec_jiffies);